Review of the functional surgical treatment of dystonia

A review of functional surgery for dystonia is presented. Recently renewed interest in stereotaxy for dystonia has followed the resurgence of pallidot omy and the introduction of deep brain stimulation (DBS) in Parkinson's dis ease (PD) in the early 1990s. However, even since the 1950s, small series o f patients treated with ablative surgery have been carefully studied, provi ding useful information, notably regarding the tolerability of surgery. In the setting of dystonia, thalamotomy was first performed with substantial b enefits, but some authors outlined the great variability in outcome, and th e high incidence of operative side-effects. In the 'modern' era of function al surgery for movement disorders, the globus pallidus internus (GPi) has e merged to be currently the best target for dystonia, based on small series of patients published in the last few years. Both bilateral posteroventral pallidotomy (PVP) and bilateral pallidal stimulation, performed by several teams, have benefited a variety of patients with severe dystonia, the most dramatic improvements being seen in primary dystonia with a mutation in the DYT1 gene. Whereas patients with secondary dystonia have often shown a les ser degree of improvement, some publications have nevertheless reported maj or benefit. There is today a strong need for carefully controlled studies c omparing secondary and primary dystonia, DYT1 and non-DYT1 dystonia, ablati ve surgery and DBS, with additional assessment of neuropsychological change s, especially in children treated with bilateral pallidal procedures.